package com.ld.xuanKe.listener;

import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.read.listener.ReadListener;
import com.alibaba.excel.util.ListUtils;
import com.ld.xuanKe.entity.*;
import com.ld.xuanKe.service.CourseService;
import com.ld.xuanKe.service.impl.CourseServiceImpl;
import org.springframework.context.ApplicationContext;
import org.springframework.web.context.WebApplicationContext;

import java.util.List;

import static org.apache.struts2.ServletActionContext.getServletContext;

public class MyUploadCourseDataListener implements ReadListener<Course> {
	/**
	 * 每隔5条存储数据库，实际使用中可以100条，然后清理list ，方便内存回收
	 */
	private static final int BATCH_COUNT = 100;
	private int all = 0;
	private int success = 0;
	/**
	 * 缓存的数据
	 */
	private List<Course> cachedDataList = ListUtils.newArrayListWithExpectedSize(BATCH_COUNT);
	/**
	 * 假设这个是一个DAO，当然有业务逻辑这个也可以是一个service。当然如果不用存储这个对象没用。
	 */

	private CourseService courseService;


	public MyUploadCourseDataListener(){
		ApplicationContext applicationContext = (ApplicationContext) getServletContext().getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
		courseService = (CourseServiceImpl) applicationContext.getBean(CourseService.class);
	}



	/**
	 * 这个每一条数据解析都会来调用
	 *
	 * @param data    one row value. Is is same as {@link AnalysisContext#readRowHolder()}
	 * @param context
	 */
	public void invoke(Course data, AnalysisContext context) {
		cachedDataList.add(data);
		// 达到BATCH_COUNT了，需要去存储一次数据库，防止数据几万条数据在内存，容易OOM
		if (cachedDataList.size() >= BATCH_COUNT) {
			saveData();
			// 存储完成清理 list
			cachedDataList = ListUtils.newArrayListWithExpectedSize(BATCH_COUNT);
		}
	}



	/**
	 * 所有数据解析完成了 都会来调用
	 *
	 * @param context
	 */
	public void doAfterAllAnalysed(AnalysisContext context) {
		// 这里也要保存数据，确保最后遗留的数据也存储到数据库
		saveData();
	}

	/**
	 * 加上存储数据库
	 */
	private int saveData() {
		all += cachedDataList.size();
			for (Course course : cachedDataList) {
				course.setSelected(0);
				int i = courseService.add(course);
				success += i;
			}
			getServletContext().setAttribute("all",all);
			getServletContext().setAttribute("success",success);
		return success;
	}
}
